'AMA::MyProduct': cannot instantiate abstract class - c++

Question

I am working on my school project that has a base class and a derived class with some other classes.
Product.h
#ifndef AMA_PRODUCT_H
#define AMA_PRODUCT_H
#include <iostream>
#include <fstream>
namespace AMA
{
const int max_sku_length = 7;
const int max_unit_length = 10;
const int max_name_length = 75;
const double TRate = 0.13;
class Product
{
private:
char m_type;
char m_sku[max_sku_length +1];
char m_unit[max_unit_length + 1];
char* m_name;
int m_Cquantity;
int m_Nquantity;
double m_price;
bool m_status;
protected:
void sku(const char* setSku) { strncpy(m_sku, setSku, max_sku_length); }
const char* name() const { return m_name; }
bool taxed() const { return m_status; }
const char* sku() const { return m_sku;}
void name(const char*);
const char* unit() const;
double price() const;
void message(const char*);
bool isClear() const;
public:
double cost() const;
bool operator==(const char* src) { return strcmp(m_sku, src) == 0; }
bool isEmpty() const { return ((m_sku[0] == '\0') && (m_name == nullptr) && (m_price == 0) && (m_Cquantity == 0)); }
int qtyNeeded() const { return m_Nquantity; }
int quantity() const { return m_Cquantity; }
int operator+=(int src) { return m_Cquantity += src; }
Product();
Product(const char* sku, const char* name, const char* unit, int qty = 0,
bool taxed = true, double price = 0.0, int qtyNeeded = 0);
Product(const Product&);
Product& operator=(const Product&);
~Product();
virtual std::fstream& store(std::fstream& file, bool addNewLine = true)const = 0;
virtual std::fstream& load(std::fstream& file) = 0;
virtual std::ostream& write(std::ostream& os, bool linear)const = 0;
virtual std::istream& read(std::istream& is) = 0;
double total_cost() const;
void quantity(int);
bool operator>(const char*) const;
bool operator>(const Product&) const;
};
std::ostream& operator<<(std::ostream&, const Product&);
std::istream& operator>>(std::istream&, Product&);
double operator+=(double&, const Product&);
}
#endif
MyProduct.h
#ifndef AMA_MY_PRODUCT_H
#define AMA_MY_PRODUCT_H
#include <fstream>
#include "Product.h"
#include "ErrorState.h"
namespace AMA {
class MyProduct : public Product {
public:
MyProduct();
MyProduct(const char* sku, const char* name, const char* unit, int qty = 0,
bool isTaxed = true, double price = 0.0, int qtyNeeded = 0);
const char* sku() const;
const char* name() const;
const char* unit() const;
bool taxed() const;
double price() const;
double cost() const;
};
class Test {
MyProduct product; // Error
const char* filename;
public:
Test(const char* file);
Test(const char* file, const char* theSku, const char* theName);
std::fstream& store(std::fstream& file, bool addNewLine = true) const;
std::fstream& load(std::fstream& file);
std::ostream& write(std::ostream& os, bool linear) const;
std::istream& read(std::istream& is);
int operator+=(int value);
bool operator==(const char* sku) const;
friend std::ostream& operator<<(std::ostream& os, const Test& test);
friend double operator+=(double& d, const Test& test);
friend std::istream& operator>>(std::istream& is, Test& test);
};
}
#endif
MyProduct.cpp
#include <iomanip>
#include <fstream>
#include <cstring>
#include "MyProduct.h"
#ifdef TAB
#undef TAB
#endif
#define TAB '\t'
using namespace std;
namespace AMA {
MyProduct::MyProduct() : Product("", "", "") {}
MyProduct::MyProduct(const char* sku, const char* name, const char* unit, int qty,
bool isTaxed, double price, int qtyNeeded) :
Product(sku, name, unit, qty, isTaxed, price, qtyNeeded) {}
const char* MyProduct::sku() const { return Product::sku(); }
const char* MyProduct::name() const { return Product::name(); }
const char* MyProduct::unit() const { return Product::unit(); }
bool MyProduct::taxed() const { return Product::taxed(); }
double MyProduct::price() const { return Product::price(); }
double MyProduct::cost() const { return Product::cost(); }
Test::Test(const char* file) : filename(file) { }
Test::Test(const char* file, const char* theSku, const char* theName) :
product(theSku, theName, ""), filename(file) { }
std::fstream& Test::store(std::fstream& file, bool addNewLine) const {
if (!product.isEmpty()) {
file.open(filename, ios::out | ios::app);
file << product.sku() << TAB << product.name() << TAB << product.unit() << TAB <<
(product.taxed() ? 1 : 0) << TAB << product.price() << TAB << product.quantity() << TAB <<
product.qtyNeeded() << endl;
file.clear();
file.close();
}
return file;
}
std::fstream& Test::load(std::fstream& file) {
char sku_[max_sku_length + 1];
char name[max_name_length + 1];
char unit[max_unit_length + 1];
int quantity, qtyNeeded;
double price_;
char taxed_;
file.open(filename, ios::in);
file >> sku_;
file >> name;
file >> unit;
file >> taxed_;
file >> price_;
file >> quantity;
file >> qtyNeeded;
file.clear();
file.close();
product = MyProduct(sku_, name, unit, quantity, taxed_ != 0, price_, qtyNeeded); //ERROR
return file;
}
std::ostream& Test::write(std::ostream& os, bool linear) const {
return product.isEmpty() ? os : (os << product.sku() << ": " << product.name() << ", quantity: "
<< product.quantity() << ", quantity needed:" << product.qtyNeeded()
<< ", Cost: " << fixed << setprecision(2) << product.cost());
}
std::istream& Test::read(std::istream& is) {
char sku_[max_sku_length + 1];
char name[max_name_length + 1];
char unit[max_unit_length + 1];
int quantity, qtyNeeded;
double price_;
char taxed_;
cout << " Sku: ";
is >> sku_;
cout << " Name (no spaces): ";
is >> name;
cout << " Unit: ";
is >> unit;
cout << " Taxed? (y/n): ";
is >> taxed_;
cout << " Price: ";
is >> price_;
cout << " Quantity On hand: ";
is >> quantity;
cout << " Quantity Needed: ";
is >> qtyNeeded;
product = MyProduct(sku_, name, unit, quantity, taxed_ != 0, price_, qtyNeeded); //ERROR
return is;
}
int Test::operator+=(int value) {
product.quantity(product += value);
return product.quantity();
}
bool Test::operator==(const char* sku) const {
return !std::strcmp(product.sku(), sku);
}
std::ostream& operator<<(std::ostream& os, const Test& test) {
return test.product.write(os, true);
}
double operator+=(double& d, const Test& test) {
return d += test.product.total_cost();
}
std::istream& operator>>(std::istream& is, Test& test) {
return test.product.read(is);
}
}
I am getting errors that I don't really know how to fix
object of abstract class type "AMA::MyProduct" is not allowed
'AMA::MyProduct': cannot instantiate abstract class
a cast to abstract class "AMA::MyProduct" is not allowed
Can someone help me out please?

Answer 1

The errors are self explanatory.
AMA::MyProduct is an abstract class, and such it cannot be instantiated directly.
A class is abstract when it has at least 1 abstract method (virtual and = 0 keywords on it). An abstract method MUST be overridden in a derived class, and you MUST instantiate that derived class, not the abstract class.
AMA::MyProduct is abstract because it does not override the 4 abstract methods it inherits from AMA::Product:
virtual std::fstream& store(std::fstream& file, bool addNewLine = true)const = 0;
virtual std::fstream& load(std::fstream& file) = 0;
virtual std::ostream& write(std::ostream& os, bool linear)const = 0;
virtual std::istream& read(std::istream& is) = 0;
You implemented them in AMA::Test instead of in AMA::MyProduct.